This application incorporates by reference Taiwanese application Serial No. 89119535, filed Sep. 21, 2000.
1. Field of Invention
The present invention relates to a method of dynamically selecting a physical layer in a network system. More particularly, the present invention relates to a method of dynamically selecting a physical layer for a network card having a plurality of physical layers by means of software polling.
2. Description of Related Art
Computers have become one of the most important inventions to affect humanity. The computer has asserted itself into the daily lives of consumers. One computer can only handle personal affairs. However, when many are linked together, this allows the users to communicate with each other as well as share resources. This linking of many computers forms a computer network. This computer network has gradually changed how humanity lives, communicate, as well as work.
Furthermore, in recent years, the introduction of the computer network into homes has become a topic of interest. In fact, the design and implementation of network-able appliances is a topic of current research. The ability of networking household appliances, either to a computer network or the Internet, will allow users to control them at a distance over the network. Appliances capable of being controlled through the network are known as information appliances (IA). The appliances together with the computers form a local area network (LAN) or a home LAN. Currently, 4-wire twisted pair (telephone line) is used to connect the IA and the computer in the Home LAN, but the 8-wire twisted pair of the Ethernet can be also used. Therefore, it is very important that a network interface card has connectors for connecting to both the telephone line and the twisted pair of the Ethernet.
FIG. 1 shows layers of Open System Interconnection (OSI) model for a general computer network. Referring to FIG. 1, the OSI model comprises a physical layer (PHY), a medium access control (MAC) layer, a driver layer and an operating system layer. The physical layer is used for connecting to the transmission medium, for example, telephone lines or twisted pair. The MAC layer is used for controlling packet receptions and transmissions, wherein the packet is the transmission unit. The operating system layer controls the MAC layer by a driver.
FIG. 2 is a schematic diagram of a network interface card (NIC) used for a local area network. The NIC 201 comprises a 4-wire twisted pair connector 203 and an 8-wire twisted pair connector 205 for respectively connecting to a telephone line and a twisted pair of the Ethernet. The 4-wire twisted pair connector 203 and 8-wire twisted pair connector 205 respectively belong to different physical layers, and as such, a user can choose any one of them to connect to the network. Generally, the data transmission rate for the telephone line is 1 Mbps (bit per second) while that of the twisted pair of the Ethernet is 10/100/1000 Mbps.
Referring to FIG. 2, after the user plugs a medium into the connector 203 or 205, the computer is booted. The operating system initializes the computer after the booting procedure so that the driver can detect and set the peripheral devices. For example, a user plugs a telephone line into the connector 203. After the user boots the computer, the driver detects that the connector 203 is connected to the telephone line, and so the MAC layer is set to be connected to a first physical layer which corresponds to the telephone line. The MAC layer can then receive and transmit packets through the first physical layer and the telephone line. Meanwhile, a second physical layer and the MAC layer are in a disconnect status.
However, if the user wants to change to a different medium to connect to the network, the computer cannot successfully change the medium when the computer is running. When the user unplugs the telephone line from the connector 203, the first physical layer sends an interrupt to the MAC layer, and the MAC layer also sends an interrupt to the driver. The driver then sets the MAC layer and the first physical layer to be disconnected. If the user connects the twisted pair of the Ethernet to the connector 205, the driver and the MAC layer can not actively detect the second physical layer corresponding to the connector 205. Therefore, the MAC layer and the second physical layer are disconnected even if the Ethernet twisted pair is connected to the connector 205. Accordingly, since the MAC layer and the second physical layer are disconnected, data cannot be received nor transmitted. In this case, the user has to reboot the computer so that the driver can detect and set the connectivity between the MAC layer and the physical layer for normal network operation. As can be seen, this is not convenient for the user.
Therefore, it is an objective of the present invention to provide a method for dynamically selecting one of physical layers from a network interface card. When different physical layers are required to be selected to meet different transmission speed, the method of the invention can dynamically select a physical layer without the need to reboot the computer. Therefore, the use of the network system can become more convenient.
According to the objective, the present invention provides a method for dynamically selecting one of physical layers for a network interface card. The physical layers have at least a first physical layer and a second physical layer which are respectively connected to a first medium and a second medium. According to the disclosure of the invention, it first triggers an interrupt service routine when the first medium disconnects from the first physical layer. A timer is activated by the interrupt service routine. An interrupt is periodically sent by the timer to trigger the interrupt service routine until the interrupt service routine detects the second medium is connected to the second physical layer. The second physical layer therefore activates, and then the correct status for the second medium is set. The timer is then stopped to terminate the method.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.